Electric discharge tube



Patented Aug. 27, 1929.

UNITED STATES PATENT OFFICE.

GUSTAV LUDWIG HERTZ, OF EINDHOVEN, NETHERLANDS, ASSIGNOR TO N. V. PHIL-IPS GLOEILAMPENFABRIEKEN, 0F EINDHOVEN, THE NETHERLANDS.

nnncrnrc mscmnen TUBE.

N0 Drawing. Application filed February 18,1925, Serial- Ne. 10,105, andin the Netherlands April 1, 1924. I

This invention relates to electric discharge tubes and more particularlyto electric discharge tubes having a positive column light for lightingpurposes. I

It is known to introduce into such discharge tubes a gaseous filling ofneon, whereby the light radiated by the said tubes acquires red colour.

It is also known to introduce into discharge tubes having a positivecolumn light a little mercury in the form of a mercury drop, in additionto a gaseous filling of neon. By reason of the heating to which the tubeduring the discharge is exposed, the mercury volatilizes and at acertain temperature the vapour pressure of the mercury increases suchthat the mercury vapour begins to participate in the discharge and thepositive light emitted by the discharge-tube is even producedessentially by radiation of mercury atoms with the result that the redcolour changes to a blue one. Discharge tubes of this kind have thedisadvanta e that if for any reason the temperature 0 the tube becomestoo' low (for example by reason of a low temperature of the surroundingopen air), the vapour pressure of the mercury may acquire such a lowvalue that the mercury practically no longer takes part in the dischargeand theblue mercury light changes to the red neon light.

Now it has been found that the said dis advantage is reduced oreliminated, if instead of neon some other rare gases are used,

for example argon, but krypton and xenon also give favourable resultAccording to the invention a gaseous fill-- ing is introduced into adischarge tube with positive column light, which gaseous fillingcomprises arggn and mercury vapor. The gaseous filling may consist of aron, kr ton, xenon and mercury vapor. referabl y a gaseous filling ofargon and mercury, the argon pressure of whlch is above 4 millimetres ofmercury will be used. Discharge tubes according to the invention arecapable of still producing mercury li ht at temperatures at which adischarge tu e having positwo light and filled with neon and mercuryalread produces neon light. This is a very remar able phenomenon, as theexciting potential of argon is lower than that of neon.

One would therefore expect that at a temperature at which a neon mercurydischarge tube produces neon light, an argon mercury ciency of dischargetubes according to the invention will likewise be greater than that. ofdischarge tubes having a positive light and a gaseous filling of neonand mercury.

' What I claim is;

1. A' discharge tube for positive column light, the gaseous filling ofwhich comprises argon and mercury vapor.

2. A discharge tube for positive column light, the gaseous filling ofwhich consists o argon, krypton, xenonand mercury vapor.

3. A discharge tube for ositive column light, the gaseous filling 0which consists o argon having a pressure above 4 millimetres of mercurypressure and of mercury vapor.

. In testimon whereof I afiix my signature, at the city January, 1925.

- GUSTAV LUDWIG HERTZ.

o Eindhoven, this 20th day of

